Iowa and New Hampshire together have just 1.4 percent of the U.S. population, which is why it is fine for them to begin the presidential selection process: Small states reward an underdog’s retail politics. New Jersey Gov. Chris Christie relishes such politics and has fresh evidence that voters are enjoying his enjoyment.

Speaking last Wednesday by phone from his home away from home, New Hampshire, he said: “People have remembered why they liked me in the first place.” His saturation campaigning there has produced a 55-point reversal of his favorable/unfavorable rating in the Granite State, from 16 points more unfavorable than favorable to 39 points more favorable than unfavorable. According to last week’s Des Moines Register/Bloomberg Politics poll, Christie’s favorability number in Iowa is 51 percent, up from 29 percent in August, when his unfavorability number was 59 percent.

Nationally, among all the Republican candidates, the ABC News/Washington Post poll finds Christie’s favorability rating “most improved,” from 35 percent in the spring to 53 percent today. He gained among conservatives (23 points), among Republicans generally (18) and among independents (14). The latter matters. As David W. Brady of Stanford University and the Hoover Institution wrote last week in the Wall Street Journal:

“The arithmetic is pretty simple: 41% of voters in the 2012 presidential election described themselves as moderates, and 29% as independents. Almost all Republicans (93% ) and self-described conservatives (82% ) voted for Mitt Romney, but that wasn’t enough. Even if Mr. Romney had won every Republican or conservative voter, it still wouldn’t have been enough. Because there are roughly 5% more Democrats than Republicans, the GOP needs a solid majority of independents to win a national election. In 2012, Mitt Romney outpolled Barack Obama among independents, 50% to 45% . But that didn’t take him across the Electoral College finish line.”

Christie has won twice statewide in a blue state that last voted for a Republican presidential candidate in 1988. He correctly says no rival for the Republican nomination has been elected in a state so inhospitable to Republicans. In New Jersey, 48 percent of registered voters are unaffiliated with either the Democratic (32 percent) or Republican (20 percent) parties. Christie won reelection with 60 percent of the vote, including 57 percent of women, 51 percent of Hispanics and 21 percent of African Americans.

Christie might benefit from Donald Trump’s caroms in this year’s political pinball machine. As Jeremy Carl of the Hoover Institution argues in National Review, Republicans cannot win with Trump or without his supporters. Christie could be an alternative alpha persona, but without the ignorance. (Check Trump on the nuclear triad.) In 2012, Republicans nominated a northeastern blue-state governor, with unsatisfactory results. Christie, however, might be an un-Romney, connecting viscerally with voters — especially whites without college educations — who in 2012 stayed away from the polls in droves.

Christie will campaign in Iowa for nine days before the Feb. 1 caucuses. If they yield a cloudy result — say, the top four finishers clustered within four points — New Hampshire will become the scythe that reduces the field. Christie plans to be “the last governor standing” when, after South Carolina at the latest, he expects former governors Mike Huckabee and Jeb Bush and current Ohio Gov. John Kasich to join current and former governors Scott Walker, Rick Perry, Bobby Jindal, George Pataki and Jim Gilmore on the sidelines.

As chairman of the Republican Governors Association in 2014, Christie campaigned frenetically, dispersing more than $100 million as 17 Republican governors were reelected and seven new ones were elected. So far, only four governors have endorsed candidates: Alabama’s Robert Bentley supports Kasich, Arkansas’s Asa Hutchinson supports Huckabee, Maryland’s Larry Hogan and Maine’s Paul LePage support Christie. So 24 Republican governors, many of them indebted to Christie and all of them disposed to admire executives, have political muscles to flex.

Sen. Ted Cruz (R-Tex.) and Trump are at last at daggers drawn, the former saying the latter has “New York values” — fighting words in most Republican circles — and the latter saying the former is not a natural- born citizen. Republicans concerned about losing control of the Senate already wonder whether vulnerable GOP senators — Illinois’s Mark Kirk, Ohio’s Rob Portman, Pennsylvania’s Pat Toomey, Wisconsin’s Ron Johnson, New Hampshire’s Kelly Ayotte — want either Trump or Cruz at the top of the ticket, or even campaigning in their states.

“I was not on the [debate] stage two months ago,” Christie says. He expects to be at the center of the stage at the Cleveland convention.

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George F. WillGeorge F. Will writes a twice-weekly column on politics and domestic and foreign affairs. He began his column with The Post in 1974, and he received the Pulitzer Prize for commentary in 1977. His new book, "The Conservative Sensibility," will release June 4, 2019. Follow